Liberal old writer has last drop of scotch with editor (4-6)
I believe the answer is:
open-handed
'liberal' is the definition.
(thesaurus)
'old writer has last drop of scotch with editor' is the wordplay.
'old writer has' becomes 'open' (I can't justify this - if you can you should believe this answer much more).
'last drop of' suggests the final letters.
'with' becomes 'and'.
'editor' becomes 'ed'.
The final letter of 'scotch' is 'h'.
'open'+'h'+'and'+'ed'='OPEN-HANDED'
(Other definitions for open-handed that I've seen before include "Generous" , "Big-hearted?" .)